± f''irc  25    - 


141903 

INSTRUCTIONS 

FOE  COIlECraC,  TESTIXG,  MELTING  AID  ASSAYING 

GOLD, 

WITH    A   DESCRIPTION    OP    THE  PROCESS    FOR    DISTINGUISHING 

NATIVE    GOLD   FROM  THE   WORTHLESS  ORES  WHICH    ARE 

FOUND  IN  THE  SAME  LOCALITY,  AM)  THE  CHEMICAL 

TESTS  AND  NECESSARY   APPARATUS  TO    BE 

USED    FOR   TESTING    GOLD,   SILVER, 

PLATINA    AND    MERCURY; 

ILLUSTRATED     WITH     30    WOOD    ENGRAVINGS, 

AND  ARRANGED  FOR  THE  USE  OF  PERSONS  WHO  ARE 
ABOUT  TO  VISIT 

THE  GOLD  REGION  OF  CALIFORNIA, 


BY  EDWARD    N.   KENT,    PRACTICAL  CHEMIST, 

No     116   JOHN-STREET,    NEW-YORK. 


The  whole  of  the  Apparatus  described  in  this  work  may  be  obtained  as 
*•     above,  at  the  prices  mentioned  in  the  Catalogue  at  the  end. 


fcj>  tlje 


NEW-YORK: 

EDWARD  N.  KENT,  PRACTICAL  CHEMIST, 
No.  116  JOHN-STREET. 

1849. 


University  of  California  •  Berkeley 

THE  PETER  AND  ROSELL  HARVEY 

MEMORIAL  FUND 


INSTRUCTIONS 

FOE  COLLECTING,  TESTING,  MELTING  AND  ASSAYING 

GOLD, 

WITH    A   DESCRIPTION    OF    THE  PROCESS    FOR    DISTINGUISHING 

NATIVE    GOLD   FROM  THE  WORTHLESS  ORES  WHICH    ARE 

FOUND  IN  THE  SAME  LOCALITY,  AND  THE  CHEMICAL 

TESTS  AND  NECESSARY  APPARATUS  TO    BE 

USED    FOR   TESTING    GOLD,    SILVER, 

PLATINA    AND    MERCURY; 

ACCOMPANIED  WITH  ENGRAVINGS. 

THE    WHOLE    BEING    SIMPLY    ARRANGED,  AND    FREE    FROM    SCI- 
ENTIFIC   TECHNICALITIES,     FOR    THE     USE     OF 
PERSONS  WHO  ARE  ABOUT  TO  VISIT 

THE  GOLD  REGION  OF  CALIFORNIA, 


BY  EDWARD    N.    KENT,    PRACTICAL  CHEMIST, 

No     116   JOHN-STREET,    NEW-YORK, 


The  whole  of  the  Apparatus  described  in  this  work  may  be  obtained  as 
above,  at  the  prices  mentioned  in  the  Catalogue  at  the  end. 


tfje 


NEW-YORK  : 

VAN   NORDEN   &   AMERMAN,   PRINTERS, 
No.  60  WILLIAM-STREET. 

1848. 


ENTERED  according  to  the  Act  of  Congress,  in  the  year  1648,  by 

EDWARD  N,  KENT, 

In  the  office  of  the  Clerk  of  the  District  Court  of  the  United  States  for  the  Southern 
District  of  New- York. 


PREFACE. 


DURING  the  present  intense  excitement  relative  to  the 
immense  amount  of  gold  found  in  California,  I  have  had 
frequent  and  anxious  inquiries  for  the  necessary  appa- 
ratus and  instructions  desirable,  to  ensure  success  in 
searching  for  gold,  platina  and  mercury.  This,  together 
with  a  knowledge  that  the  greater  proportion,  in  fact, 
nearly  all  of  the  persons  who  are  fitting  out  for  the  gold 
legion,  are  unacquainted  with  chemistry,  and  there  being 
no  single  work  containing  the  necessary  information  in  a 
small  space,  has  induced  me  to  publish  this  little  work. 

As  the  book  is  intended  for  this  purpose  only,  and 
for  immediate  use,  it  has  necessarily  been  written  in 
great  haste,  and  consequently  without  that  care  which 
should  be  used  in  the  publication  of  a  work  on  any  sci- 
entific subject ;  but  being,  as  before  stated,  not  for  the 
use  of  students,  but  simply  as  a  hand-book  for  gold 
seekers,  I  put  it  before  them,  trusting  that  they  will 
attach  the  proper  inference  to  my  motives  in  its  publi- 
cation, and  derive  a  benefit  from  its  perusal. 

EDWARD  N.  KENT. 


INSTRUCTIONS 

FOR 

COLLECTING,  TESTING,  1ELTING  AND  ASSAYING  GOLD, 


CHAPTER  I. 

ANALYSIS  OF  NATIVE    GOLD    FOUND    IN    CALIFORNIA 

ITS    EXTERNAL    APPEARANCE SITUATIONS    IN 

WHICH    IT    IS    FOUND PROCESS  AND   APPARATUS 

FOR    WASHING    THE    GOLD CARE   NECESSARY  TO 

DISTINGUISH  THE  REAL  GOLD  FROM  THE  WORTH- 
LESS    ORES    FOUND     IN     THE     SAME     LOCALITY 

SOURCES    FROM    WHICH    SPECIMENS    HAVE    BEEN 
OBTAINED. 

HAVING  lately  analyzed  three  specimens  of  ore 
from  California,  all  of  which  were  supposed  by  the 
possessors  to  contain  gold,  a>nd  finding  but  one  of 
them  that  proved  to  contain  it>I  am  convinced  that 
the  native  gold  is  found  in  the  same  localities  as 
some  worthless  ores,  having  a  yellow  colour,  and 
which  are  often  collected  or  bought  under  the  im- 
pression that  the  latter  are  valuable. 

The  object  of  this  work  is,  therefore,  to  give 
such  plain  and  simple  instructions  for  distinguish- 
ing the  real  gold  from  the  spurious,  that  the  most 
humble  individual  may  be  able  to  protect  himself 


CALIFORNIA    GOLD. 


from  the  imposition  of  knaves,  and  prevent  a  waste 
of  time  and  labour,  in  saving  only  such  minerals 
as  are  really  valuable.  I  shall,  therefore,  confine 
myself  to  such  directions  as  will  be  suitable  for 
persons  who  are  supposed  to  be  entirely  unac- 
quainted with  chemistry. 

The  native  gold  found  in  California  occurs  in 
small,  regular,  flattened  grains  or  spangles,  which 
show  by  their  ovoid  shape  and  smooth  edges,  that 
this  is  their  original  form,  and  that  they  are  not 
broken  off  from  a  greater  mass.  It  is  found  mixed 
with  the  sands  of  the  plains  and  rivers,  and  when 
washed  from  dirt  is  of  a  dull  orange  colour,  and 
on  analysis  proves  to  consist  almost  entirely  of 
pure  gold,  with  a  small  quantity  of  silver.  It  is 
found  most  plentifully  at  low  water,  and  after 
storms  or  temporary  floods. 

In  the  present  state  of  affairs  in  California,  the 
operator  should  be  furnished  with  a  few  wooden 
bowls,  holding  from  one  to  two  gallons.  A  portion 
of  the  earth  containing  the  metallic  spangles  is  to 
be  put  into  one  of  the  bowls,  filling  it  from  one 
quarter  to  one  third  full.  It  is  then  to  be  mixed: 
up  with  water,  by  stirring  with  a  stick,  and  while 
the  earthy  matter  is  still  suspended  in  the  liquid,, 
it  is  to  be  poured  off,  the  gold,  from  its  greater 
weight,  having  previously  settled  to  the  bottom. 
This  process  of  washing  is  to  be  continued  re- 
peatedly, upon  the  same  portion,  until  the  water 
flows  off  clear,  and  the  gold  is  left  in  shining  span- 
gles at  the  bottom.  This  is  to  be  taken  out  and 


PROCESS    OF    WASHING.  7 

carefully  preserved  in    a  well-corked   vial,    and 
then  a  new  portion  of  earth  treated  as  before. 

Gold  very  often  exists  in  such  small  grains  that 
it  is  almost  invisible  when  mixed  with  the  earthy 
matters,  and  doubtless  large  quantities  are  now 
overlooked  and  lost,  from  inability  to  obtain  it  by 
washing  only.  These  fine  particles  may  be  ob- 
tained as  follows  :  The  earth  is  mixed  up  with 
water  as  before,  but  is  allowed  to  settle  a  little 
longer  before  decanting  off  the  water,  for  fear  of 
losing  the  small  particles.  The  time  allowed  for 
settling,  before  pouring  off  the  water  at  each  wash- 
ing, must  be  regulated  according  to  the  relative 
density  of  the  earthy  matters,  and  of  the  gold  to  be 
separated  ;  for  instance,  after  mixing  the  earth  well 
with  the  water,  it  may  be  left  to  settle  for  a  half 
minute,  then  *poured  off;  mixed  again  with  water, 
settled  for  half  a  minute,  and  again  poured  off, 
and  so  on  repeatedly  till  the  residue  is  clean,  al- 
though it  may  still  contain  grains  of  sand.  If,  on 
examination  of  the  residue  with  a  small  pocket 
microscope,  (Fig.  1,) 


Fig.  1. 


it  is  found  to  consist  principally  of  gold,  this  shows 
that  the  earthy  matters  and  sand  having  been 
washed  away  so  cleanly,  that  some  metallic  par- 


8  AID    OF    THE    MICROSCOPE. 

tides  may  have  been  washed  away  with  them. 
In  order  to  prove  this,  some  of  the  last  washings 
of  the  next  operation  should  be  saved  in  a  bowl, 
allowed  to  settle,  and  then  examined  with  the  mi- 
croscope. If  these  washings  contain  gold,  a  longer 
time,  say  three  quarters  of  a  minute,  to  a  minute 
or  more,  must  be  allowed  for  settling  at  each 
washing,  so  as  to  allow  the  gold  to  subside  before 
the  water  is  poured  offi  It  is  impossible  to  give 
the  exact  time  that  the  mixture  should  be  allowed 
to  settle  before  it  is  poured  off,  as  this  depends 
entirely  upon  circumstances.  This,  however,  can 
with  a  little  care  be  so  arranged  that  no  gold  will 
be  lost,  because  this  metal  is  heavier  than  all  other 
bodies  except  platina,  and  will  consequently  set- 
tle first  when  mixed  with  lighter  bodies. 

When  the  gold  is  plentiful,  and  found  in  such 
large  grains  as  to  be  visible  to  the  naked  eye,  and 
the  small  particles  are  not  present,  this  extreme 
care  in  washingmay  be  dispensed  with,  because  the 
large  grains  require  no  further  treatment  after  be- 
ing washed  clean  ;  but  where  the  gold  is  in  such 
a  minute  state  of  division  as  to  be  invisible  with- 
out the  aid  of  the  microscope,  it  must  be  obtained 
from  the  residue  by  the  process  called  amalgama- 
tion, or  by  melting  in  a  crucible  with  a  suitable 
flux  ;  but  as  these  operations  require  some  in- 
struction in  the  use  of  chemical  apparatus,  I  shall 
defer  tbe  description  of  them  for  the  present,  and 
devote  the  whole  of  the  third  chapter  to  that  im- 
portant subject.. 


BEST    METHOD    OF    WASHING.  9 

The  most  simple,  and  probably  the  best  method 
of  washing  gold  to  separate  it  from  earthy  matters 
is  practised  in  some  parts  of  Europe,  as  follows: 
The  washing  is  performed  in  a  wooden  bowl  or  dish, 
formed  like  a  very  flat  cone, 
(Fig.  2,)  and  which  is  fro 
15  to  18  inches  in  diameter, 
and  3  or  4  inches  deep.  It  Fig.  2. 

requires  some  skill  in  order  to  perform  this  opera- 
tion to  advantage.  The  dish  filled  with  about  20 
pounds  of  the  earth  or  sand  containing  gold,  is 
carried  into  a  river,  if  possible,  where  the  operator 
stands  above  his  knees  in  water,  protected  with 
india  rubber  boots,  which  come  up  to  the  thighs. 
The  dish  is  plunged  into  the  stream,  and  the  mix- 
ture stirred  up  with  the  hand ;  the  dish  is  dex- 
terously whirled  in  such  a  manner,  that  at  each 
gyration  it  is  inclined  at  different  angles,  so  as  to 
allow  the  matters  suspended  in  the  water  to  flow 
out,  while  the  gold  remains  at  the  bottom,  in  the 
angle  of  the  cone.  The  washing  is  to  be  repeated 
till  the  gold  is  left  clean;  it  is  then  transferred 
into  a  small  iron  dish  and  dried. 

If  the  above  shaped  bowls  cannot  be  obtained, 
those  sold  at  the  wooden  ware  stores  must  be  pur- 
chased. But  those  with  conical  bottoms  are  much 
better,  as  they  retain  the  gold  in  a  small  space. 
Vessels  of  wood  are  preferred  to  metal,  as  the 
slight  roughness  of  the  interior  prevents  the  little 
particles  of  gold  from  sliding  out,  and  being  buoy- 
ant, they  can  be  left  at  rest  on  the  surface  of  the 
water,  when  necessary,  without  danger  of  sinking. 


10  ANALYSIS    OF    SPECIMENS. 

Two  of  the  spurious  samples  which  I  have 
analyzed,  somewhat  resemble  gold  in  external  ap- 
pearance. They  are  in  small  bright  pieces,  not 
uniform  in  shape,  and  of  a  light  yellow  colour, 
more  brilliant  than  pure  gold,  but  containing 
principally  copper  and  arsenic,  with  traces  of  zinc 
and  iron.  This  ore  seems  to  be  found  in  Cali- 
fornia in  large  quantities,  and  from  the  fact  of  its 
metallic  appearance  and  yellow  colour,  it  is  diffi- 
cult for  one  unacquainted  with  such  matters  to 
distinguish  it  from  pure  gold,  without  resorting  to 
chemical  tests. 

Another  sample  required  but  a  slight  examina- 
tion to  prove  that  it  was  iron  pyrites.*  A  part  of 
it  is  in  pieces  of  irregular  size  and  shape,  and  some 
is  in  well  formed  cubical  crystals.  It  is  very 
brittle,  breaking  easily  under  the  hammer,  and 
strikes  fire  with  steel.  On  the  outside  of  the  min- 
eral the  colour  is  dark  brown,  inside  it  is  bronze 
yellow.  These  characters  are  sufficient  to  identify 
this  ore  without  a  chemical  examination. 

One  of  the  samples  containing  copper,  and  also 
the  iron  pyrites,  were  handed  to  me  for  examination 
by  the  editor  of  one  of  our  city  papers,  who  in- 
formed me  that  he  received  them  from  a  person  who 
bought  them  in  the  vicinity  of  the  California  mines. 


*  Iron  Pyrites,  which  is  a  bisulphuret  of  iron,  contains  45  pr.  ct. 
of  iron,  and  54  of  sulphur.  It  is  used  in  the  arts  for  making  sulphur, 
sulphuric  acid,  and  sulphate  of  iron.  The  residue  of  some  of  these 
processes,  is  an  oxide  of  iron  called  colcothar  in  commerce. 


ANALYSIS    OF    SPECIMENS.  11 

The  other  sample,  containing  copper,  was  hand- 
ed to  me  by  a  person  who  said  that  he  received 
it  from  one  of  the  soldiers  of  Col.  Stevenson's 
regiment. 

The  sample  of  real  gold  which  I  analyzed  and 
found  pure,  was  presented  to  me  by  one  of  the 
firm  of  a  large  commission  house  in  this  city,  who 
assured  me  that  they  received  it  direct  from  a 
brother  of  one  of  the  firm  who  resides  in  San 
Francisco ;  this  sample  being  from  a  lot  contain- 
ing about  $9,000  worth  of  gold. 

Not  having  been  in  California  personally,  I  am 
obliged  to  give  the  statements  of  other  individuals 
(without,  however,  doubting  their  truth)  as  to  the 
sources  from  which  all  of  the  above  specimens 
were  obtained.*  But  the  analyses  of  all  the  sam- 
ples I  performed  myself.  Specimens  of  those 
which  I  have  tested  may  be  seen  at  No.  116  John- 
street,  N.  Y. 


*  The  following  extract  is  from  a  letter,  dated  California,  Sept. 
9th,  1848,  which  appeared  in  the  New-York  Sun,  Dec.  20th.  As 
I  noticed  the  letter  just  as  these  sheets  were  going  to  press,  I  con- 
cluded to  publish  it,  as  it  is  a  singular  confirmation  of  the  statements 
I  have  made  on  the  same  subject : 

"  I  have  in  my  possession  upwards  of  sixty  pounds  of  it  pure, 
besides  a  great  quantity  which,  for  want  of  means,  I  am  unable  to 
separate  from  the  mineralogical  incrustations  which  enclose  it. 

"  But  there  are  also  other  substances  to  be  found  here  which  resem- 
ble gold,  and  which  have  deceived  many  who  thought  themselves  rich 
in  the  possession  of  it.  Copper  and  platina  in  great  quantities  have 
been  dug  up  and  thrown  by  unnoticed.  From  my  tent,  in  which  I 
am  now  writing,  I  can  see  at  least  two  or  three  thousand  dollars 
worth  of  these  metals." 


CHAPTER  II. 

APPARATUS       AND       TESTS      NECESSARY      FOR      DIS- 
TINGUISHING  PURE    GOLD  FROM    THE  SPURIOUS 

TESTS     FOR    GOLD,     SILVER,    PLATINA    AND    MER- 
CURY  PROBABLE    PRESENCE     OF     PLATINA     AND 

MERCURY  IN  CALIFORNIA MINOR  DIRECTIONS  TO 

BE     FOLLOWED     TO     PREVENT    A    POSSIBILITY    OF 

FAILURE FOUNDATION       FOR       THE      STUDY       OF 

CHEMISTRY. 


Fig.  3. 


THE  chemical  operation  of  testing  a  mineral 
is  very  simple,  when  the  proper  apparatus  and 
tests  are  at  hand,  and  for  this  purpose  the  author 
has  prepared  a  large  number  of  test  chests, 
neatly  fitted  up  and  furnished  with  all  the 
apparatus  and  reagents  necessary  for  testing, 
gold,  silver,  copper,  iron,  platina  and  mercury, 
with  a  separate  division  in  the  chest  for  each 
article,  and  with  a  lock  and  key,  as  represented  in 

Fig.  a. 


CONTENTS   OF   THE  TEST  CHEST. 


13 


The  possessor  of  one  of  these  chests  can,  by  proper 
attention  to  the  plain  and  simple  directions  given  in 
this  chapter,  test,  on  the  spot,  any  of  the  minerals 
he  may  find,  and  thus  prevent  the  possibility  of 
failure. 

The   Test  Chest  contains  the  following   pure 

CHEMICALS  AND  APPARATUS  : 

4  oz.  Nitric  Acid,  in  a  glass  stoppered  bottle. 
8    "  Hydrochloric  Acid,  in  2        "  " 

1    "  Protochloride  of  Tin,  in  a      "  " 

1    "  Protosulphate  of  Iron,  "  " 

1    "  Solution  of  Ammonia,  "  " 

1    "  Chloride  of  Ammonium,        "  " 


Small  porcelain  Mortar  and 
Pestle,  for  pulverizing  ores,  &c. 
Fig.  4. 


Fig.  4. 


Fig.  5. 


10. 


Scales,  for  weighing  gold,  and  a  set  of  Troy 
Weights,  from  20  dwts.  to  1  grain.     Fig,  5. 

2 


14  TESTING  FOR  GOLD. 

Small  graduated  Measure,  with  divisions  of  one 
drachm  into  60  minims.  Fig.  6. 

Six  test  Tubes,  for  testing  solutions.     Fig.  7. 

Brass  spirit  Lamp,  for  travelling,  with  screw 
cap  to  prevent  leaking.  Fig.  8. 

Glass  Funnel,  and  24  small  filters  to  suit. 
Fig.  9. 

Two  small  Flasks,  for  dissolving  rnetals.  Fig.  10. 

The  operation  of  testing  gold  is  to  be  performed 
as  follows  :  A  small  quantity  of  the  metal,  which 
need  not  be  more  than  a  few  grains  in  weight,  is  to 
be  put  into  one  of  the  flasks.  Nitric  acid  is  then 
poured  into  the  graduated  measure  till  it  is  filled  to 
the  line  marked  20 ;  the  acid  is  then  poured  into 
the  flask,  and  a  gentle  heat  is  now  to  be  applied  to  it 
by  the  aid  of  the  spirit  lamp.  If  the  metal  be  gold 
it  will  not  dissolve,  and  the  acid  will  remain 
colourless;  but  further  tests  must  be  tried  before 
it  can  be  proved  to  be  gold. 

Fill  the  graduated  measure  to  the  line  marked 
60  with  hydrochloric  acid,  and  add  this  to  the 
nitric  acid  already  in  the  flask ;  then  mix  the  two 
together  by  whirling  the  flask.  This  mixture  of 
twenty  parts  of  nitric  with  sixty  of  hydrochloric 
acid  (or  one  to  three)  is  called  aqua  regia,  which 
is  the  only  practical  solvent  for  gold. 

If  the  metal  be  gold,  it  will  dissolve  slowly 
when  heated  in  the  aqua  regia,  furnishing  a  deep 
yellow  solution.  The  mixture  should  be  heated  at 
least  fifteen  minutes,  and  even  boiled,  when  the 


PROOFS    OF    GOLD    AND    SILVER.  15 

action  becomes  quiet,  in  order  to  decompose  the 
nitric  acid  ;  an  excess  of  which  would  interfere 
with  the  following  tests.  When  there  is  no  longer 
any  evolution  of  gas  in  the  flask,  it  is  to  be  filled 
to  the  top  of  the  neck  with  clear  rain  water,  closed 
with  the  thumb,  and  the  contents  well  mixed. 
If  the  solution  is  not  clear,  it  must  first  be  filtered 
into  the  graduated  measure,  or  another  flask, 
through  a  filter  made  by  folding  one  of  the  circular 
papers  into  a  quadrant,  and  placing  it  when  opened 
into  a  funnel.  The  solution  being  then  put  into 
the  funnel  lined  with  the  porous  paper,  passes 
through,  leaving  the  dirt  upon  the  filter. 

A  small  quantity  of  the  clear  solution  is  then 
put  into  two  test  tubes.  A  few  drops  of  protochlo- 
ride  of  tin  is  then  added  to  the  solution,  in  one  of 
the  test  tubes,  and  a  few  drops  of  protosulphate 
of  iron  is  added  to  the  other.  If  a  purple  precipi- 
tate is  produced  in  the  first  tube,  and  a  very  fine 
brown  powder  or  blackish  blue  coloration  is  pro- 
duced in  the  second,  these  are  positive  proofs  that 
the  metal  is  gold. 

If  the  nitric  acid  alone  dissolves  the  metal,  and 
the  solution  remains  colourless,  (or  only  slightly 
tinged  blue,)  a  portion  of  the  solution  is  put  into  a 
perfectly  clean  test  tube,  and  then  a  few  drops  of 
hydrochloric  acid  added.  If  a  white  precipitate 
is  produced  on  the  addition  of  this  acid,  this  is 
evidence  that  the  metal  is  silver,  but  is  further 
proved  as  follows :  close  the  top  of  the  test  tube 


16  TESTS     FOR   COPPER   AND    IRON. 

with  the  thumb,  and  shake  it  well,  then  allow  the 
precipitate  to  settle ;  decant  off  the  clear  liquid 
above,  and  add  a  little  ammonia.  If  silver,  the 
white  precipitate  will  dissolve,  and  will  again  pre- 
cipitate if  a  little  nitric  acid  is  added  to  the  solu- 
tion in  ammonia.  The  white  precipitate  is  chlo- 
ride of  silver,  which  is  soluble  in  ammonia,  but 
insoluble  in  acids.  Another  proof  of  silver  is,  that 
when  the  above  white  chloride  is  exposed  to  day- 
light, (especially  sunshine,)  it  speedily  becomes 
dark  coloured. 

If  the  nitric  acid  dissolves  the  metal,  and  the 
solution  becomes  blue,  it  may  be  a  mixture  of 
silver  and  copper,  or  copper  only.  Put  a  little  of 
the  solution  into  a  test  tube,  and  add  a  few  drops 
of  hydrochloric  acid.  If  the  solution  contains  sil- 
ver, a  white  precipitate  will  be  produced,  which  is 
soluble  in  ammonia.  The  colour  being  blue  is  a 
sufficient  test  for  copper ;  but  if  the  solution  is  so 
dilute  as  to  prevent  a  decision  as  to  the  colour,  a 
few  drops  of  ammonia  added  will  produce  a  clear 
solution  of  a  fine  azure  blue  colour. 

If  the  nitric  acid  dissolves  the  metal,  and  the 
solution  becomes  of  a  deep  reddish  brown  colour, 
the  metal  is  iron,  which  is  further  proved  by  put- 
ting a  little  of  the  solution  into  a  test  tube,  and 
then  adding  ammonia  till  the  mixture  smells  of  it 
after  being  well  shaken.  If  iron,  a  copious  pre- 
cipitate of  a  reddish  brown  colour  will  be  produced, 
which  is  the  peroxide  of  iron. 


TESTS    FOR    PLATINA.  17 

According  to  late  reports,  platina  is  also  found 
in  California.  This  is  very  probable,  as  the  two 
metals  are  generally  found  in  the  same  localities. 
I  therefore  think  it  advisable  to  give  a  short  de- 
scription of  platina,  and  the  method  of  testing  it, 
so  that  the  finder  may  be  enabled  to  know  this 
valuable  metal,  which  in  its  native  state  is  worth 
about  three  or  four  times  as  much  as  silver. 

Platina  is  found  in  small  shining  spangles  or 
grains  of  about  the  same  size  and  form  as  gold, 
but  of  a  different  colour ;  this  metal  being  white 
like  silver.  It  can  be  easily  distinguished  from 
silver,  by  heating  it  in  a  flask  with  nitric  acid. 
Silver  dissolves  readily  when  heated  in  this  acid, 
and  gives  a  colourless  solution,  unless  contaminated 
with  copper,  in  which  case  the  solution  has  a  shade 
of  blue.  But  platina  is  insoluble  in  nitric  acid, 
although  it  is  sometimes  contaminated  with  other 
metals ;  the  latter  of  which  may  dissolve,  leaving 
the  platina  unacted  upon. 

Platina,  like  gold,  dissolves  in  aqua  regia  when 
heated.  The  solution  is  of  a  deep  reddish  brown 
colour,  resembling  that  from  iron,  but  it  is  easily 
distinguished  from  that  metal  and  all  others,  by  the 
addition  of  a  small  quantity  of  chloride  of  ammo- 
nium. If  the  metal  in  solution  be  platina,  this  last 
test  will  give  a  precipitate  of  a  yellow  colour,  which 
is  positive  proof  'that  the  metal  is  platina. 

There  is  no  doubt  of  the  existence  of  mercury 
(quicksilver)  in  California.  I  have  tested  a  sam- 
ple of  the  ore  said  to  have  been  obtained  there, 

2* 


18  TESTS    FOR    QUICKSILVER. 

and  it  proved  to  contain  mercury,  by  the  following 
process,  which  is  adapted  to  be  used  with  the 
articles  in  the  test  chest. 

The  ore  from  which  mercury  is  extracted  is 
called  cinnabar.  When  pure,  it  has  the  same  com- 
position as  the  vermillion  of  commerce. 

The  sample  from  California  which  I  examined 
appeared  to  be  impure,  being  so  hard  as  to  strike 
fire  with  steel.  It  is  difficult  to  reduce  it  to 
powder.  The  ore,  in  mass,  is  of  a  dull  red 
colour,  which  when  powdered  appears  brighter. 
A  small  quantity  heated  in  a  flask  with  aqua  regia 
(1  part  nitric  to  3  of  hydrochloric  acid)  till  the 
red  colour  was  destroyed,  left  a  white  powder, 
which  is  evidence  of  an  impurity.  The  solution 
was  then  diluted  with  four  or  five  parts  of  water, 
and  filtered.  A  few  drops  of  ammonia  added  to 
the  clear  solution  (to  neutralize  the  excess  of  acid) 
gave  a  white  precipitate,  which  was  re-dissolved 
by  the  addition  of  one  or  two  drops  of  hydro- 
chloric acid. 

A  few  drops  of  this  solution  were  put  on  a  clean 
plate  of  copper,  (a  cleaned  cent  answers,)  it  soon 
caused  a  dark  spot,  and  after  being  left  a  few 
minutes,  it  was  rubbed  off  with  a  cloth,  a  white 
spot  of  metallic  mercury  was  left. 

Protochloride  of  tin,  added  to  another  por- 
tion of  the  solution,  gave  a  white  precipitate  at 
first,  but  by  adding  more  of  the  solution  of  tin, 
the  precipitate  was  converted  into  a  gray  powder, 


METALLIC    MERCURY.  19 

which,  when  boiled  with  hydrochloric  acid,  united 
into  a  globule  of  metallic  mercury.* 

By  heating  powdered  cinnabar,  mixed  with  its 
weight  of  quick-lime,  to  redness  in  an  iron  retort, 
the  mercury  is  separated  and  distils  over.  For 
small  operations,  the  retort  described  in  Chapter 
III.  will  answer,  but  for  manufacturing  purposes 
on  the  large  scale,  I  refer  to  Dumas's  Traite  de 
Chimie,  t.  iv.  p.  306 — 323,  or  Ure's  Dictionary 
of  the  Arts,  article  Mercury. 

I  have  now  described  all  of  the  tests  necessary  to 
distinguish  gold,  silver,  platina  and  mercury;  and 
to  insure  success  in  testing  for  these  metals,  a  few 
words  are  necessary,  in  regard  to  some  minor  di- 
rections, which  if  properly  followed  will  prevent  a 
possibility  of  failure. 

The  operator  should  be  careful  to  well  wash 
each  article  of  apparatus  after  it  has  been  used, 
and  never  use  the  same  flask,  test  tube,  or  funnel, 
for  two  different  purposes,  without  washing.  Care 
must  also  be  used  that  the  chemicals  do  not 
become  contaminated,  by  being  accidentally  mixed 
with  one  another.  A  single  drop  of  the  contents 
of  one  bottle  falling  into  another,  may  spoil  it  in 


*  The  last  test  is  not  very  easy  to  perform,  even  in  the  hands  of  a 
chemist.  The  dark  mixture  requires  to  be  boiled  a  long  time  in 
order  to  unite  the  globules  of  mercury  into  one.  With  the  micro- 
scope,  the  little  globules  can  be  readily  discovered,  even  when  there  ia 
no  appearance  of  metallic  mercury  to  the  naked  eye.  The  first  test 
will  generally  be  sufficient  to  prove  the  presence  of  mercury  in  an  ore. 


20  REWARD    OF    STUDY. 

such  a  manner,  that  although  no  difference  in  the 
colour  of  the  liquid  may  be  visible,  it  would  give 
a  different  reaction  from  the  pure  article,  and  thus, 
when  applied  for  testing  would  produce  fallacious 
results,  perplexing  to  the  operator  and  injurious 
to  his  interests.  After  the  glasses  have  been  well 
washed,  they  should  be  dried  before  putting  them 
away  in  the  box ;  otherwise  the  moisture  will  be 
likely  to  injure  the  box,  and  after  a  time  deface 
the  labels,  so  that  the  different  tests  cannot  be 
distinguished  from  each  other. 

By  careful  attention  to  the  above  directions,  the 
operator  will  have  the  satisfaction  of  reaping  a 
rich  reward  for  his  trouble,  and  will  probably  lay 
the  foundation  of  a  love  for  the  study  of  the  en- 
chanting science,  which  teaches  the  nature  and 
composition  of  bodies,  and  explains  the  beautiful 
phenomena  which  he  will  have  witnessed  while 
performing  the  chemical  experiments  described 
in  these  pages. 


CHAPTER  III. 

AMALGAMATION— MELTING  GOLD— FURNACES— CRU- 
CIBLES  FLUXES FUEL TONGS,    ETC. 

THE  process  of  amalgamation  is  used  to  sepa- 
rate the  noble  metals  from  the  ore  or  matrix,  when 
they  exist  in  such  small  particles  as  to  be  invisible, 
and  consequently  cannot  be  picked  out  by  hand. 

On  the  large  scale,  the  ores  are  ground  and 
amalgamated  in  mills  constructed  for  the  purpose, 
and  composed  of  two  stones.  The  lower  one  is 
stationary,  and  enclosed  in  a  rim  or  case,  while  the 
upper  revolves  by  the  aid  of  water  or  steam  power. 
The  ore  is  first  stamped,  then  ground  to  powder 
between  the  stones,  and  subsequently  mixed  with 
metallic  mercury,  which  forms  an  amalgam  with 
the  gold. 

It  is  hardly  probable  that  the  readers  of  this 
little  work  will  operate  so  extensively  as  to  re- 
quire the  use  of  steam  or  water  power.  I  shall 
therefore  describe  in  detail  the  whole  process  of 
separating  gold  by  amalgamation,  but  confine 
myself  to  the  use  of  such  apparatus  and  means 
as  can  be  readily  obtained  without  a  great  outlay 
of  capital. 

Gold  often  exists  in  veins,  and,  when  mined,  is 
mixed  more  or  less  with  stony  gaugue.  In 


22 


PROCESS    OF    AMALGAMATION. 


Fig.  11. 


this  case  the  ore  is  first  to  be  stamped  in  an  iron 
mortar,  (Fig.  11,)  and  then  reduced  to  powder  by 
pulverizing  in  one  of  porcelain.    Fig.  12.     A  small 
quantity  of  metallic  mercury  is 
then  poured  into  the  mortar,  and 
the  mixture  ground  together  un- 
til the  gold  is  dissolved,  which 
is  judged  of  as  follows  :     By 
adding  at  first  but  a  very  small 
quantity  of  mercury,  it  will  soon 
combine  with  the   gold   when 
(  ground  as  directed,  and  form  a 
solid  amalgam.     A  little  more 
mercury    is    then    added,    the 
grinding  continued,  and  so  on 
Fig.  12.  repeatedly  till  the  mercury  no 

longer  becomes  solid  by  further  grinding.  Water 
is  then  added,  and  mixed  well  with  the  contents 
of  the  mortar  to  wash  out  the  dirt,  which  is 
separated  by  decanting  off  the  water.  After  a 
few  washings  in  this  way  the  residue  will  become 
clean,  and  is  then  to  be  wiped  dry  with  a  cloth 
or  sponge.  A  piece  of  chamois  leather  is  now 
to  be  spread  out  in  a  basin  or  bowl,  and  the 
amalgam  of  mercury  and  gold  poured  into  it. 
The  corners  and  edges  of  the  leather  are  then  to  be 
gathered  up,  so  as  to  form  a  bag,  with  the  amalgam 
at  the  bottom  ;  it  is  tied  tightly  with  a  stout  string, 
and  the  contents  squeezed  as  strongly  as  possible, 
by  pressing  and  twisting  the  bag,  by  which  ope- 
ration a  fluid  portion  of  mercury  containing  a  little 


SEPARATION  OF  THE  GOLD  AND  MERCURY.       23 

gold  is  separated  by  passing  through  the  pores  of 
the  skin.  This  fluid  portion  is  preserved  by  itself, 
and  is  to  be  used  in  the  commencement  of  another 
operation  on  a  fresh  portion  of  ore. 


Fig.  13. 


Fig.  14. 


A  solid  amalgam  of  mercury  and  gold  remains 
in  the  bag,  which  is  to  be  taken  out  and  placed 
in  the  iron  retort.  Fig.  13.  A  little  lute,  made 
by  mixing  powdered  pipe  clay  into  a  paste  with 
water,  is  put  on  the  rim  of  the  retort,  and  after 
putting  on  the  cover,  it  is  screwed  down  tightly  by 
means  of  the  clamp.  The  retort  is  then  placed 
in  a  furnace,  and  heated  slowly,  at  first,  to  expel 
moisture,  then  gradually  raised  to  a  low  red  heat. 
The  end  of  the  retort  is  meantime  placed  in  a 
small  India  rubber  bag  resting  in  a  vessel  filled 
with  cold  water,  to  condense  the  mercury  which 
distils  over  and  is  collected  in  the  bag. 

When  no  more  mercury  distils  over,  the  opera- 
tion is  finished.  The  gold  remaining  in  the  crucible 
is  of  a  dull  colour,  and  in  a  porous  mass.  It  is 
to  be  transferred  to  a  small  crucible,  mixed  with 


24  MELTING    GOLD. 

a  little  borax,  and  melted  in  the  furnace  by  a 
strong  fire  urged  with  a  double  bellows.  The 
fused  contents  of  the  crucible  are  then  poured  into 
a  conical  ingot  mould.  Fig.  14.  This  mould  is 
formed  like  a  tall  wine  glass,  and  from  its  conical 
shape  is  well  adapted  for  a  small  or  large  quantity 
of  metal.  When  the  product  is  cold,  the  flux  is 
to  be  separated  from  the  metal  by  the  aid  of  a 
hammer. 

If  the  quantity  of  solid  amalgam  obtained  at 
one  operation  is  but  small,  the  results  of  several 
amalgamations  should  be  reserved  for  one  distil- 
lation, because  it  is  but  a  little  more  trouble  to 
distil  as  much  as  will  fill  the  retort,  than  one 
quarter  of  that  quantity  ;  and  a  smaller  proportion 
of  mercury  is  lost,  which  is  an  important  consi- 
deration. 

The  gold  obtained  in  the  above  process  is  more 
or  less  pure,  according  to  the  quality  of  the  ore. 
It  almost  always  contains  a  portion  of  silver,  the 
amount  of  which,  and  the  standard  of  fineness  of 
the  gold,  is  to  be  ascertained  by  the  process  of 
assaying,  which  will  be  described  in  the  fourth 
chapter,  together  with  the  process  of  refining 
gold. 

For  melting  gold,  a  strong  fire  is  necessary,  and 
the  operation  is  generally  performed  in  a  forge  or 
furnace.  The  following  is  a  description  of  a  new 
form  of  furnace,  invented  by  the  author,  and  which 
is  admirably  calculated  for  melting  in  crucibles, 
for  the  distillation  of  mercury,  for  cupellation,  and 


DESCRIPTION    OF    FURNACE. 


25 


for  every  other  chemical  operation  requiring  the 
use  of  a  furnace  : 


Fig.  15,  a. 


15,  b. 


(Fig.  15,)  front  view,  (a.)  Side  view,  (b.)  Sand- 
bath  for  retorts,  (c.)  Sand-bath  for  evaporating, 
(d.)  Stopper  for  pipe,  (e.) 

This  furnace  is  14  inches  high,  (not  including 
the  dome,)  and  7  inches  diameter.  It  is  made  of 
strong  plate  iron,  and  lined  with  the  most  refrac- 
tory fire  clay.  It  has  six  doors  ;  one  in  the  dome 
for  feeding  with  coal  in  crucible  operations,  one  in 
the  middle  of  the  front  for  feeding,  while  distilling 
or  evaporating,  and  for  a  muffle  in  cupel  opera- 
tions, and  one  at  the  bottom  for  air  ;  one  door  on 
each  side,  for  iron  or  porcelain  tubes,  or  for  hold- 
ing an  iron  bar  to  support  the  end  of  a  muffle,  and 
one  door  in  the  side  at  top,  for  the  neck  of  a  retort 
or  sand-bath.  There  is  a  small  pipe  at  the  bottom, 
to  attach  a  bellows,  and  thus  convert  this  into  a 

blast  furnace. 

8 


26 


HESSIAN    CRUCIBLES. 


There  are  two  pipes  for  connecting  with  the  flue 
of  the  laboratory,  one  at  the  top,  to  be  used  in  cru- 
cible operations,  and  the  other  at  the  back,  to  be 
used  when  evaporating. 

The  stopper  (e)  is  to  close  either  of  these  pipes 
when  not  in  use. 

There  are  two  sand-baths,  one  (c)  for  retorts, 
and  one  (d)  made  double,  for  evaporations. 

The  dome  is  lined  with  fire  clay,  and  is  used 
when  a  great  heat  is  required. 

The  whole  furnace  is  made  in  the  most  careful 
manner,  of  strong  and  durable  materials. 

For  obtaining  the  greatest 
heat  which  can  be  produced 
by  the  above  furnace,  a 
double  bellows  (Fig.  16) 
should  be  connected  with 
the  small  pipe  at  the  bottom  of  the  furnace,  by 
means  of  a  bent  iron  pipe,  formed  so  as  to  raise 
the  bellows  a  few  feet  from  the  floor. 

For  melting  gold,  and  other  metals, 
good  crucibles  are  required.     Of  these 
there  are  different   kinds  ;  those   most 
.     generally  used  for  metals  are  the  Hes- 
\        /      sian.     (Figs.  17  and  18.)     These  cruci- 
bles are  imported  in  nests,  and  may  be 
had  of  different  sizes,  in  shape  either 
round  or  triangular.     They  are   gene- 
rally without  covers,  and  as  a  substitute 
for  these,  a   smaller   crucible  inserted 
within  a  larger  one  may  be  used. 
18. 


Fig.  16. 


Fig.  17. 


FRENCH    CRUCIBLES.  27 

The  French  crucibles,  (Fig.  19,)  manufactured  by 
M.  Beaufaye,  in  Paris,  and  used  by  the  French 
chemists  and  refiners  instead  of  the  Hessian,  are 
far  superior  to  the  above,  being  particu- 
larly remarkable  from  their  power  of 
well  supporting  alterations  of  tempera- 
ture ;  but  unfortunately  they  cost  too 

£ J  high  to  be  generally  used  in  this  country. 

Fig.  19.  A  full  description  of  them  may  be  found 
in  Dumas's  Traite  de  C/iimie,  t.  2,  p.  691. 

In  the  use  of  crucibles  for  melting  gold,  the 
smallest  which  can  be  employed  is  the  best,  as  it 
requires  less  heat  to  fuse  the  metal,  and  the  loss 
in  the  operation  is  not  so  great;  but  when  gold 
exists  in  mixture  with  earthy  or  stony  particles, 
these  are  to  be  powdered  and  fused  with  a  flux, 
and  in  this  case  a  much  larger  crucible  is  required, 
on  account  of  the  evolution  of  carbonic  acid,  or 
swelling  of  the  mass. 

The  use  of  the  flux  is  to  dissolve  the  stony  par- 
ticles, forming  with  them  a  glass  or  slag.  It  also 
cleans  the  surface  of  the  particles  of  metal  when 
heated  with  it,  so  as  to  cause  them  to  unite  and  fuse 
into  a  globule  or  button,  at  the  bottom  of  the  crucible. 

Fluxes  of  different  kinds  are  used  according  to 
the  purpose  required,  but  for  most  all  crucible 
operations  with  gold  and  silver,  a  mixture  of  one 
part  of  the  ore  with  three  parts  of  a  flux  composed 
of  equal  parts  of  carbonate  of  potash*  and  of  nitre, 

*  Carbonate  of  potash  is  the  salt  of  tartar  of  commerce,  and  of 
which  **  pearlash"  is  an  impure  variety. 


28  FLUXES    AND    FUEL. 

will  answer  an  excellent  purpose.  Th.e  carbonate 
of  potash  in  this  flux  dissolves  the  silica,  &c.,  in 
the  ore,  and  cleans  the  surface  of  the  metal,  while 
the  nitre  destroys  dirt  and  other  organic  matters, 
and  at  the  same  time  oxydizes  any  copper  which 
may  be  present,  causing  it  to  become  dissolved 
in  the  flux. 

When  gold  or  silver  free  from  gaugue  is  to  be 
melted,  they  require  no  other  flux  than  a  little 
borax  to  cause  the  particles  to  unite  in  a  button, 
its  use  being  exactly  analogous  to  that  of  rosin 
when  used  by  the  tinsmith  in  soldering. 

An  important  consideration  in  crucible  opera- 
tions is  the  choice  of  fuel.  In  England,  coke  is 
generally  used,  either  alone  or  mixed  with  char- 
coal ;  but  in  America  it  is  difficult  to  obtain  coke, 
and  consequently  we  are  obliged  to  use  anthra- 
cite or  charcoal.  No  better  fuel  than  charcoal 
would  be  needed  if  it  did  not  burn  away  so  fast ; 
this  is  its  only  disadvantage,  as  it  burns  freely,  with- 
out any  clinker,  and  does  not  fuse  together;  but  the 
softer  kinds  of  anthracite,  such  as  peach  orchard 
coal,  fuse  at  a  high  heat,  stick  to  the  crucible, 
and  form  large  quantities  of  clinker  in  the  fur- 
nace, which  makes  it  very  unpleasant  to  use.  The 
best  kind  of  anthracite  is  the  Lehigh  coal.  This 
does  not  ignite  quite  so  readily  as  the  softer  kinds, 
but  it  contains  less  earthy  matters,  and  conse- 
quently does  not  fuse  in  the  furnace  or  form  much 
clinker. 


CHARCOAL    AND    LEHIGH.  29 

The  best  fuel  for  the  crucible  furnace  is  a  mix- 
ture of  charcoal  and  Lehigh.  The  fire  is  to  be 
commenced  with  charcoal,  in  small  pieces ;  a  little 
Lehigh  is  then  to  be  added,  and  so  on  alternately 
as  the  fire  burns  freely;  first  charcoal  and  then 
Lehigh  is  to  be  added. 

In  short  operations,  and  even  in  those  which 
require  a  strong  fire  for  some  time,  charcoal  alone 
may  be  used  where  economy  is  no  object ;  but  in 
this  case,  constant  care  is  required  in  supplying 
the  furnace  with  fuel.  In  the  process  of  cupel- 
lation,  charcoal  only  is  used. 

Where  fluxes  are  used,  a  small 
iron  ladle  (Fig.  20)  is  very  con- 
venient for  putting  them  into  the 
Fig.  20,        crucible,  which,  when  large,  may 
be  heated  to  redness  before  the  materials  are  in- 
troduced, and  thus  cracks  may  be  discovered  be- 
fore a  loss  of  substance  has  taken  place. 

Suitable  tongs  are  indispensable  in  these  opera- 
tions. The  smallest,  (Fig.  21,)  8  inches  long,  for 
very  small  crucibles;  (Fig.  22,)  16  inches  long, 
made  light,  and  used  principally  for  charcoal ; 
(Fig.  23,)  2  feet  long,  is  the  best  kind  for  general  ope- 
rations. A  moderate  sized  crucible,  if  not  too  heavy, 
may  be  lifted  out  of  the  furnace,  and  the  contents 
poured  out  with  these  tongs ;  but  if  the  crucible 
is  heavy,  a  piece  might  be  broken  out  of  the  side, 
and  the  contents  lost.  To  avoid  this,  tongs  are 
made  of  the  form  of  Fig.  24  ;  these  are  two  feet 
long,  and  made  so  as  to  clasp  round  a  crucible  to 
3* 


30 


TOOLS    FOR   FURNACE. 


Fig.  22. 


Fig.  21. 


Fig.  23. 


Fig.  25.  Fig.  24. 

take  it  out  of  the  furnace.  Those  represented  in 
Fig.  25,  are  then  used  to  pour  out  its  contents.  It 
is  therefore  almost  absolutely  necessary  to  be  pro- 
vided with  a  pair  of  each  kind  of  tongs  in  order  to 
suit  all  contingencies.* 


*  For  a  full  description  of  all  other  chemical  operations  and 
apparatus,  I  refer  the  reader  to  a  new  work  called  "  Chemical  and 
Pharmaceutical  Operations,"  by  Campbell  Morfit,  practical  chemist, 
Philadelphia. 

This  work  contains  upwards  of  400  illustrations,  and  will  be  a 
valuable  assistant  to  all  who  are  engaged  in,  or  contemplate  the 
study  of  chemistry. 


CHAPTER  IV. 

TOUCHSTONE    AND    NEEDLES — CUPELLATION — PART- 
ING,     OR      QUARTATION STANDARD      OF      GOLD 

REFINING    OF    GOLD    AND    SILVER. 

THERE  are  three  methods  for  ascertaining  the 
quality  of  gold,  viz.,  by  the  touchstone  and 
needles,  by  cupellation,  and  by  parting  or  quar- 
tation. 

The  first  is  the  process  which,  from  its  simpli- 
city and  convenience,  is  used  by  jewellers  and 
others  for  learning  at  a  glance  the  value  of  the 
articles  which  they  buy  and  sell,  and  which  are 
composed  of  gold,  alloyed  with  different  propor- 
tions of  silver  or  copper;  and  this  is  ascertained  by 
making  a  comparison  between  the  specimen  under 
examination  and  others  of  known  value.  The 
test  is  made  upon  a  black  silicious  mineral  called 
a  touchstone,  which  is  a  variety  of  jasper  known 
as  the  Lydian  stone ;  arid  the  specimens  with 
which  the  alloys  are  compared,  are  points  of  gold 
alloyed  with  different  proportions  of  silver  and 
copper,  attached  to  small  bars  of  silver,  each  marked 
with  the  number  of  carats  of  which  the  point  is 
composed.  These  bars  are  connected  together  by 
a  silver  wire,  as  represented  in  Fig.  26. 


32 


TOUCHSTONE     AND    NEEDLES. 


12 


13 


21 


22 


23 


24 


Sometimes  the  points  are  at- 
tached to  a  brass  plate  in  the  form 
of  a  star.  The  points  on  each 
are  numbered  from  6  to  24,  being 
alloys  from  6  to  24  carats  fine. 

When  an  article  is  to  be  tested 
by  this  process,  a  corner  of  it  is 
to  be  rubbed  on  the  stone  in  such 
a  manner  as  to  form  a  mark 
about  ~  of  an  inch  wide,  and 
i  an  inch  long.  A  touch  needle, 
resembling  in  colour  the  speci- 
men under  examination,  is  then 
Fig.  26.  rubbed  in  the  same  manner,  so 
as  to  form  a  mark  on  the  stone  near  to,  and  of  the 
same  size  as  the  first.  A  drop  of  the  acid  mixture 
(which  will  be  described  shortly)  is  then  put  upon 
the  two  marks,  and  particular  notice  is  to  be 
taken  of  the  difference  in  the  marks  produced  by 
the  acid.  If  the  spot  produced  by  the  article 
examined,  is  brighter  than  that  from  the  needle, 
this  shows  that  it  is  better  than  the  quality  of  that 
needle ;  and  if  it  is  not  as  bright,  that  it  is  not  so 
good.  If  no  difference  can  be  seen,  this  shows 
that  the  specimen  examined  is  of  the  degree  of 
fineness  marked  on  the  needle.  After  a  fewr  trials 
the  operator  will  find  the  needle  corresponding 
with  the  specimen  he  wishes  to  test. 

With  a  little  experience,  this  process  gives  re- 
sults, correct  within  one  carat,  which  is  sufficiently 
near  for  commercial  purposes. 


PROCESS    OF    CUPELLATION.  33 

The  test  acid  used  with  the  above  needles  is 
composed  of  98  parts  nitric  acid,  of  specific  gravity, 
1.34,  2  parts  hydrochloric  acid,  sp.  gr.  1.17,  and 
25  parts  of  distilled  water.     The 
acid  is  kept  for  use  in  a  low  glass 
bottle,  with  a  long  tapering  stop- 
per,   which     nearly    touches    the 
bottom.    (Fig.  27.)    When  used,  a 
drop  of  the  acid  is  to  be  taken  out 
on  tne  end  of  the  stopper. 
The    process    of    cupellation   is    an    ingenious 
method  of  separating  foreign  metals   from  silver 
or  gold,  by  means  of  lead.     To  perform  this  ope- 
ration, the  furnace  described   in  Chapter  III.  is 
well  adapted.     A  vessel  of  refractory  fire-clay, 
resembling  a  small  oven,  and 
called  a  muffle,  (Fig.  28,)  is  put 
into  the  furnace,  the  front  end 
Jg«  ^y»  of  the  muffle  being  supported  by 

the  lower  opening,  or  door,  in  the  front,  and  the  back 
rests  on  asmall  barof  iron  put  through  the  two  small 
doors  at  the  side.  A  good  charcoal  fire  is  then  to  be 
made,  with  the  front  door  closed  ;  and  when  the 
muffle  is  bright  red-hot,  a  perfectly  dry  cupel 
is  put  into  it.  Metallic  lead,  weighing  about 
|  of  the  weight  of  the  cupel,  is  then  put  into  it, 
and  when  the  lead  is  fused,  a  portion  of  the  gold 
to  be  assayed  (about  T!¥*  of  its  weight)  is  to  be 


*  When  silver  is  assayed  by  cupellation,  a  portion  weighing  l-5th 
of  the  weight  of  the  lead  may  be  employed. 


34  METHOD    OF    MAKING    CUPELS. 

wrapped  in  a  thin  piece  of  sheet  lead,  or  blotting 
paper,  and  introduced  into  the  melted  metal.  A 
good  fire  is  now  to  be  kept  up,  and  the  front  door 
then  opened  so  as  to  allow  air  to  pass  through  the 
muffle,  which  causes  the  lead  to  oxydize,  and 
become  converted  into  litharge,  which  dissolves 
the  impurities  in  the  alloy  of  gold,  and  is  then 
absorbed  by  the  porous  cupel.  Towards  the  last 
of  the  operation,  the  melted  metal  moves  round 
rapidly,  and  becomes  dull ;  suddenly  the  agitation 
ceases,  the  button  becomes  very  brilliant  and  im- 
movable. This  is  the  end  of  the  cupellation,  and 
is  called  the  brightening. 

The  cupel  is  then  to  be  left  in  the  muffle  for  a 
few  minutes,  and  drawn  gradually  towards  the 
mouth,  before  it  is  taken  out,  so  that  it  may  cool 
slowly.  The  button  is  then  taken  off,  brushed 
and  weighed.  Its  weight  compared  with  that  of 
the  alloy  used,  gives  the  percentage  of  fine  gold. 
With  practice  and  good  management  cupel- 
lation becomes  easy,  and  is  quickly  performed; 
and  although  it  does  not  give  results  which  are 
exactly  correct,  it  is  sufficiently  so  for  most  pur- 
poses, and  it  is  the  process  generally  in  use  by 
goldsmiths  for  assaying  gold  and  silver. 

The  cupels  used  for  this  process  are  made 
of  powdered  bone-ash,  as  follows  :  4  Ibs.  of 
the  ash  are  well  mixed  with  lib.  of  beer;  the 
bottom  ring  of  a  cupel  mould  (Fig.  29)  is  then 
filled  with  the  mixture,  and  the  handle 
pressed  down ;  this  gives  form  to  the  cu- 
Fig.29.  pel;  the  ring  is  then  turned  over,  and  the 


PARTING    OR    QUARTATION.  35 

cupel  removed  by  pressing  on  the  bottom.     When 
dried  and  ignited  it  is  ready  for  use. 

The  only  process  which  is  absolutely  correct 
for  assaying  gold,  is  that  in  use  at  the  mint,  and  is 
called  parting,  or  quartation. 

Small  portions  of  the  specimen  to  be  assayed 
are  cut  off  from  different  parts  of  the  ingot,  so  as 
to  get  a  fair  sample  of  it.  Twelve  grains  of  the 
metal  are  then  carefully  weighed  on  a  delicate 
balance  (and  for  making  a  correct  assay  a  deli- 
cate balance  is  necessary,  together  with  a  set  of 
accurate  assay  weights,  made  for  the  purpose.) 
The  balance  represented  in  Fig. 
30  is  the  kind  employed.  It  is 
enclosed  in  a  glass  case,  with  a 
sliding-door,  to  keep  it  from  dust 
and  currents  of  air,  while  weigh- 
ing. The  set  of  platina  weights 
Fig.  30.  contains  12,  6,  5,  3,  2,  1,  1,  1,  {, 
j'-,  _»_  grains.  These  are  made  very  carefully 
from  the  standard  used  in  the  mint. 

Having  previously  ascertained  the  comparative 
value  of  the  alloy,  by  means  of  the  touchstone, 
12grs.  are  carefully  weighed  and  mixed  with  a 
proportion  of  silver,  which,  added  to  that  already  in 
the  alloy,  shall  make  the  proportion  of  silver  equal 
21  times  the  weight  of  the  fine  gold.  The  mixture 
of  gold  and  silver  is  then  cupelled  with  twice  its 
weight  of  lead.  The  resulting  button  is  flattened 
by  a  hammer,  then  rolled  out  into  a  thin  ribbon, 


36  STANDARD    OF    GOLD. 

about  2  inches  long.  This  is  to  be  wound  on  a  quill 
or  pencil,  so  as  to  form  a  thin  spiral,  which  is  to  be 
put  into  a  small  flask,  of  the  capacity  of  3  ounces. 
2oz.  of  nitric  acid,  of  22°,  (sp.  gr.,  1.16)  is  then 
poured  on,  and  the  mixture  heated  for  3  or  4 
minutes.  Then  replace  the  first  acid  with  2oz.  of 
that  which  is  32°,  or  stronger,  (sp.  gr.  1.26,)  boil  ten 
minutes,  then  replace  with  fresh  acid  of  32°.,  and  boil 
ten  minutes  longer.  The  residue  of  gold,  which  is 
of  a  dull  red  colour,  is  to  be  washed  well  in  the  flask, 
and  then  transferred  to  a  small  crucible,  dried  and 
heated  without  fusion.  It  is  then  to  be  carefully 
weighed  on  the  assay  balance. 

The  standard  of  gold  is  expressed  by  the  term 
carat  in  commerce,  and  in  thousandths  by  govern- 
ment. Pure  gold  is  24  carats  or  If  fine  :  18  carats 
fine  is  1 1  pure,  &c.  Expressed  in  thousandths, pure 
gold  is}§JJfine:  18  carats  fine  is  therefore  jVWj&c. 
Example.  If  in  the  process  of  parting,  the  pure 
gold  remaining  weighs  11  grains,  this  is  \\  or  f  £ 
pure.  That  is,  in  24  parts  of  the  sample  assayed, 
there  is  22  parts  of  pure  gold.  It  is  consequently 
22  carats  fine. 

If  we  wish  to  express  this  in  thousandths,  in  the 
absence  of  a  table,  it  is  easily  performed  by  the 
rule  of  proportion  :  as  f  J  i§  a  whole,  so  is  j  J£J. 
In  this  example  we  have  an  alloy  22  carats  fine ; 
now  the  following  statement  expresses  the  thou- 
sandths :  as  24  is  to  1000  so  is  22. 


RULE    FOR    CALCULATION.  37 

24    :     1000     :     :    22 
22 


2000 
2000 


24)     22000     (916 

91  (\ 

«w  JL  \J 

1000 

40 
24 


160 
144 


To  save  the"  trouble  of  calculation,  tables  are 
drawn  up.  By  doubling  the  weight  of  the  pure 
assay,  the  number  of  carats  is  given.  On  looking 
down  the  left  hand  column  of  the  table,  this  num- 
ber is  found,  and  opposite  to  it  is  the  decimals 
expressing  the  thousandths. 

EXAMPLE. 

Suppose  in  an  assay  of  12  grs.  of  an  alloy,  we 
have  left  10}  grs.  of  gold.  Doubling  10£,  we 
have  20{  carats. 

Opposite  20  we  find    .     .     0.833 
«         j  ..     .     0.010 

0.843  thousandths. 
Or,  expressed  in  vulgar  fractions,    843 

1.00.0 
4 


38 


CARATS  REDUCED  TO  THOUSANDTHS. 


ASSAY  TABLE, 

FOR  REDUCING  CARATS  TO  THOUSANDTHS. 


24  carats 

_ 

.     1.000 

23       " 

, 

.     0.958 

22       "          . 

• 

.     0.916 

21       "           . 

• 

.     0.875 

20       « 

i 

.     0.833 

19       «           . 

• 

.     0.79  L 

18       "           . 

• 

.     0.750 

17       "          , 

• 

.     0.708 

16       «          .         . 

- 

.     0.666 

15       "          . 

• 

.     0.625 

14       "          . 

» 

.     0.583 

13       "          . 

• 

.     0.541 

12       "          . 

§ 

.     0.500 

11       "          . 

•, 

.     0.458 

10       «          . 

.     0.416 

9"          . 

• 

.     0.375 

8       " 

.     0  333 

7       " 

" 

.     0.291 

6       " 

• 

.     0.250 

5  -     "          . 

g 

.     0.208 

4       « 

^ 

.     0.166 

3 

. 

.     0.125 

2 

• 

.     0.083 

1 

• 

.     0.041 

JL          *' 

. 

.     0.020 

i           < 

. 

.     0.0  10 

I     ;      '     ' 

• 

.     0.005 

• 

.     0.002 

£  •     •     • 

• 

.     0.001 

Gold  is  refined  by  a  process  called  quartation 
which  is  similar  to  that  used  for  assaying. 

The  impure  gold  is  melted  with  about  3  parts 
(3  times  its  weight)  of  silver ;  it  is  stirred  well 
in  the  crucible  so  as  to  have  a  perfect  mixture ; 
and  this  is  poured  into  a  large  dish  of  water,  which 


REFINED    GOLD    AND    SILVER.  39 

is  kept  ill  motion  by  an  assistant,  who  stirs  it  with 
a  stick  while  the  alloy  is  being  poured  in.  By 
this  process  the  metal  is  divided  into  small  lumps, 
which  are  more  easy  to  act  upon  with-  acid  than 
when  in  mass.  The  granulated  metal  is  then  put 
into  a  large  glass  flask,  and  heated  on  a  sand 
bath,  with  twice  its  weight  of  nitric  acid  diluted 
with  an  equal  measure  of  water.  When  the  ac- 
tion ceases,  a  little  more  acid,  stronger  than  the 
first,  is  put  on  and  heated  again  till  there  is  no 
action.  The  acid  is  poured  off,  and  the  gold  re- 
maining in  powder  is  washed  several  times,  till  a 
portion  which  comes  off  will  give  no  precipitate 
when  mixed  with  a  solution  of  common  salt. 

The  gold  is  then  taken  out,  dried,  melted  with 
a  little  borax,  and  poured  into  water,  or  an  ingot 
mould.  This  is  refined  gold. 

The  solution  in  nitric  acid  is  diluted  with  water, 
to  form  2  or  three  times  its  original  measure.  Plates 
of  copper  are  then  immersed  in  it,  and  allowed 
to  remain  24  hours  or  more,  till  the  silver  is  all 
precipitated,  and  the  solution  no  longer  contains  sil- 
ver. This  is  ascertained  by  taking  out  a  small 
portion  of  the  blue  liquid,  and  if  it  gives  no  pre- 
cipitate on  the  addition  of  a  solution  of  common 
salt,  it  contains  no  more  silver.  It  is  then  to  be 
washed  repeatedly  with  water  till  the  blue  colour 
is  entirely  removed.  Dilute  sulphuric  acid  is  then 
added,  and  allowed  to  cover  it  for  a  few  hours.  It  is 
then  washed  again,  till  the  washings  are  tasteless* 
The  gray  powder  of  silver  is  then  dried  and  melted 
with  a  little  borax.  The  product  is  refined  silver* 


CATALOGUE   OF   PRICES 


APPARATUS    AND    CHEMICALS 

DESCRIBED  IN  THIS  WOKE,  AND  FOR  SALE  BY  THE  AUTHOR, 

At  116  John-street,  New-York, 


APPARATUS. 


Fig.  1.  Microscope $1  00 

"  2.  Wooden  Bowl 

Iron  Dish 15 

M  4.  Mortar 50 

"  5.  Scales  and  Weights,  3  00 
41  6.  Graduated  Measure,  75 
"  7.  J'  doz.  Test  Tubes...  25 
*»  8.  Brass  Spirit  Lamp...  125 

'*  9.  Glass  Funnel 12 

"  10.  2  Small  Flasks 38 

"  11.  Iron  Mortar... $5  to  700 
41  12.  Porcelain  Mortar....  150 

Chamois  Leather....  1  00 

"  13.  Iron  Retort 5  00 

••  14.  Ingot  Mould 3  00 

"  15.  Furnace 30  00 

«  16.  Bellows 500 


20. 
21. 
22. 
23. 
24. 
25. 
26. 

27. 

28. 
29. 
30. 


Hessian  Crucibles,      25 

Do.  Triangular,       12 

French  Crucible...       38 

Ladle  ................       37 

Tongs,  8  in.  long..  1  00 
"      16     "  1  50 

"     bent  points..  2  00 
"     clasp  ..........  2  50 

"     round  points,  2  25 
Touch  Needles...  .10  00 

Stone  .......  2  00 

Bottle  &  acid  for  do.      75 
Muffle  ................      50 

Cupel  Mould  .......  2  00 

Assay  Balance  .....  30  00 

"     Wts.  platina.  3  00 
"     Flask,  3  oz..      25 


CHEMICALS, 

Citric  Acid,  22°  (sp.gr.  1.16)..... $  gallon,  including  bottle,  $1  25 

"     32°  (    "      1.26) i      ••  "  "         1  50 

Hydrochloric  Acid,  strong,  for  Aqua  Regia...       "  "          1  00 

Mixture  of  Carbonate  of  Soda  and  Nitre,  for  Flux per  Ib.       25 

Borax,  25  cts.  per  Ib Bone  Ashes,  for  Cupels.. "     "        25 


The  complete  set  of  Apparatus  and  Chemicals  described  in  this 
book,  and  all  of  which  are  intended  for  persons  about  to  visit  Cali- 
fornia, can  be  put  up  in  a  short  time,  ready  for  shipping  or  mule  trans- 
portation. The  price  of  the  complete  set,  including  packing  and 
boxes,  is  $120  00. 


The  author,  being  established  in  business  as  a  practical  chemist,  is 
prepared  to  analyze  ores,  minerals,  and  all  other  articles,  at  the  short, 
est  notice,  and  on  reasonable  terms. 


CHEMICAL  APPARATUS, 


CHEMICALS 


PURE    REAGENTS 


THE  subscriber  has  on  band,  and  is  constantly  manufacturing, 
every  description  of  Chemical  Apparatus  and  Pure  Chemicals; 
and  having  established  Agencies  in  Berlin,  Hamburgh)  Bremen, 
London  and  Paris,  he  is  prepared  to  furnish  AmeriCa-H  Chemists 
with  the  same  description  of  Apparatus  as  that  used  by  Liebig, 
Fresenius,  Rose,  Dumas,  and  other  continental  Chemists. 

Among  the  Apparatus  will  be  found  Hetorts,  Receivers,  Cop- 
per Stills,  Alkalimeters,  Bottles,  Funnels,  Flasks,  Gas  Bottles, 
Graduated  Measures,  Woulfe's  Bottles,  Hydrometers,  Precipi- 
tating Glasses,  Galvanic  Batteries,  Test  Tubes,  Specific  Gravity 
Bottles,  Thermometers,  Glass,  Lead  and  India-rubber  Tubes, 
Crucibles,  Evaporating  Dishes,  Mortars,  Blowpipes,  Balances, 
Weights,  Lamps,  Platina  Crucibles,  Capsules,  Wire  and  Foil, 
Furnaces,  Gas  Bags,  and  the  latest  and  most  approved  form  of 
Apparatus  for  the  Oxy- Hydrogen  Blowpipe  and  Drummond 
Light. 

Having  an  extensive  Manufacturing,  and  also  an  Analytical 
Laboratory,  connected  with  his  establishment,  he  manufactures, 
and  has  now  on  hand,  an  extensive  assortment  of  Chemically 
Pure  Reagents,  and  is  prepared  to  furnish  Analyses  of  Ores, 
Minerals,  Potash,  Soda,  Manganese,  and  all  other  articles,  at 
the  shortest  notice. 

EDWARD  N.  KENT, 

Practical  Chemist, 
116  John-street,  New- York. 


